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name: musubix-c4-design description: Guide for creating C4 model design documents. Use this when asked to create architecture designs, system context diagrams, container diagrams, or component diagrams following the C4 model methodology. license: MIT

MUSUBIX C4 Design Skill

This skill guides you through creating C4 model architecture designs for MUSUBIX projects.

Overview

The C4 model provides four levels of abstraction for describing software architecture:

1. Context - System boundaries and external actors
2. Container - Technology choices and deployable units
3. Component - Internal structure of containers
4. Code - Implementation details (optional)

Prerequisites

Before creating designs:

1. Read requirements from storage/specs/ (REQ-* files)
2. Check steering/structure.ja.md for architecture guidelines
3. Review steering/tech.ja.md for technology constraints

Design Document Template

Copy# DES-[CATEGORY]-[NUMBER]: [Design Title]

## メタデータ
- **作成日**: YYYY-MM-DD
- **トレーサビリティ**: REQ-XXX-NNN

## 1. Context Level

### システムコンテキスト図
[External actors and systems that interact with our system]

### 外部アクター
| アクター | 説明 | インタラクション |
|---------|------|-----------------|
| User | システム利用者 | Web UI経由でアクセス |

## 2. Container Level

### コンテナ構成
| コンテナ | 技術 | 責務 |
|---------|------|------|
| Web App | React/Next.js | UI提供 |
| API Server | Node.js/Express | ビジネスロジック |
| Database | PostgreSQL | データ永続化 |

### コンテナ間通信
[Describe how containers communicate]

## 3. Component Level

### [Container Name] コンポーネント

| コンポーネント | 種別 | 責務 | 依存先 |
|---------------|------|------|--------|
| XxxService | Service | ビジネスロジック | XxxRepository |
| XxxRepository | Repository | データアクセス | Database |
| XxxController | Controller | リクエスト処理 | XxxService |

## 4. 設計パターン

### 適用パターン
| パターン | 適用箇所 | 理由 |
|---------|---------|------|
| Repository | データアクセス層 | 永続化の抽象化 |
| Service | ビジネス層 | ロジックの集約 |
| Factory | オブジェクト生成 | 生成ロジックの分離 |

## 5. 非機能要件への対応

### セキュリティ
- 認証: [方式]
- 認可: [方式]
- データ保護: [方式]

### スケーラビリティ
- [スケーリング戦略]

### 可用性
- [可用性設計]

C4 Diagram Syntax (Mermaid)

Context Diagram

Copyflowchart TB
    subgraph External["外部システム"]
        User[ユーザー]
        ExtAPI[外部API]
    end
    
    subgraph System["対象システム"]
        App[アプリケーション]
    end
    
    User --> App
    App --> ExtAPI

Container Diagram

Copyflowchart TB
    subgraph Containers["コンテナ構成"]
        Web[Web App<br/>React]
        API[API Server<br/>Node.js]
        DB[(Database<br/>PostgreSQL)]
    end
    
    Web --> API
    API --> DB

Component Diagram

Copyflowchart TB
    subgraph APIServer["API Server"]
        Controller[Controller]
        Service[Service]
        Repository[Repository]
    end
    
    Controller --> Service
    Service --> Repository

Design Patterns Reference

Domain-Specific Components

Use npx musubix design generate to get domain-specific component recommendations for 62 domains.

Output Location

Save design documents to:

Copystorage/design/DES-[CATEGORY]-[NUMBER].md

Related Skills

• musubix-ears-validation - Requirements validation
• musubix-code-generation - Generate code from design
• musubix-adr-generation - Document architecture decisions